Looper mechanism for sewing machines



Sept. 5, 1939. F. A. KUCERA LOOPBR MECHANISM FOR SEIING MACHINES Filed Feb. 19, 193? 2 Sheets-Sheet 1 INVENTOR: Frank 2?: ifuwra, By M ATTORNEYS.

p 5, 1939. F. A. KUCERA 2,172,321

LOOPER MECHANISM FOR SEWING MACHINES Filed Feb. 19, 1937 2 Sheets-Sheet 2 Ham. 1 70.12 '1 l 15 13 22 25 JJRV E Z] l l9\ 3 2w I I 5;. 1M M l w w L J, 1E 17 5 II Y 10 20 m 20 21 I m 21 I M Z0 WITNESSES- E 32 35 -30 ll?) INVENTOR: {a Frank .1? ifuwra,

W BY WTORNEYS.

Patented Sept. 5, 1939 Frank .A. Kucer Special Mac poratlon of Illinois v Application February 19, 1937, Serial No. 126,58

8 Claims. (Cl. 112-200) This invention relates to looper mechanism for sewing machines; and it is concerned more particularly with looper mechanism for feed-ofI-thearm sewing machines, of the general type featured in United States Patent No. 1,912,959, granted to Frederick F. Zeier et al., July 6, 1933.

With the patented arrangement, the looper carrier must be axially shifted on the looper shaft before it can be independently turned part way about said shaft to render the loopers accessible for ready threading.

Thus, in the event that the sewing machine is started without restoration of the looper carrier to its normal position, the loopers are apt to be injured or broken through impact with the feed dog or other contiguous parts of the machine mechanism which they ordinarily clear when in their normal planes of operation.

My invention has for its contingencies of the sort referred to.

chief aim to preclude This objective I realize in practice as hereinafter more fully disclosed, through provision of holder means whereby the looper carrier is restrained against endwise movement on the looper shaft, and associated latch means whereby said carrier is locked to the shaft with capacity for being released so that it can be swung to a limited extent about said shaft for threading of the loopers.

Another object of my invention is to attain the above advantages in a looper mechanism of the character indicated embodying a latch means which is of simple and compact construction and easier to operate than latch devices heretofore designed to serve a similar purpose.

Other objects and attendant advantages will appear from the following detailed description of the attached drawings, whereof Fig. I is a fragmentary view showing the front end of the worksupporting arm of a feed-ofI-the-arm sewing machine partly in side elevation and partly in longitudinal section, with the looper mechanism of my invention exposed.

ig. II is a transverse section taken as indicated by the arrows IIII in Fig. I but with the loopers shown in their normally retracted positions.-

Fig. III is a view like Fig. II but with the loopers swung back beyond their normal retracted positions for threading.

Fig. IV is a plan view of the looper assembly with the loopers in the fully advanced or needle loop-taking positions.

Fig. V is a view'partly in elevation and partly in section taken as indicated by in Fig. IV.

the arrows V-V ments to the loopers a, Chicago, 111., assigiior to Union hine Company, Chicago, 111;, a cor- Fig. VI is a. fragmentary sectional view taken as indicated by the arrows VI-VI in Fig. V.

Figs. VII and VIII are perspective views of two component elements of my improved looper mechanism- Fig. IX is a fragmentary detail section taken as indicated by the arrows IXIX in Fig. II,

being journaled in bearings whereof one is indicated at 3. Under the'influence of suitable actuating mechanism (not shown) the shaft I is os- 20 cillated and reciprocated endwise to impart looptaking and shedding, and needle-avoiding move- 4 (of which there are three in the present instance) incident to coaction of the latter with as many needles 5 to form a mul- 25 tiple row seam after a manner well known in the art. The loopers S operate beneath a throat plate 6 which is secured by one or more screws I to the top of the work-supporting arm 2, and are protected by a, cap 8 which is removably held in 30 place over the end of said arm by a spring pressed keeper shown at 9 in Fig. I. Above the throat plate 6 is a presser foot I!) which opposes a feed dog II mounted upon the forward yoke-like end I2a of a feed bar I2 (see Fig. II), which latter 35 extends longitudinally above the shaft I within the work-supporting arm 2. By suitable means partly shown at I3, the feed bar I2 is moved back and forth and up and down, with attendant impartation of the necessary feed and lift movements to the feed d'og II.

In accordance with the present invention, the loopers 4 are curved concentrically with the axis of the shaft I and supported in circumferentially offset relation by a carrier I5 which is separately 45 illustrated in perspective in Fig. VIII. As shown in Fig. VI, the tubular portion I6 of the carrier I5 freely embraces a holder in the form of a sleeve II, which holder is separately illustrated in Fig. VII, and which is secured by screws l8 to the 50 forward end of the shaft I with capacity for both longitudinal and rotative adjustment thereon. The carrier I5 is held against endwise movement between a shoulder I9 of the sleeve I! and a nut collar 20 threadedly engaging the outer end of 'ance of a latch pin said sleeve. An additional nut collar 2I is relied upon to prevent accidental rotation of the collar 29 after assembling of the parts. As shown in Figs. I, IV, V, and VI, the loopers 4 have anchorage shanks 22 with apertures for passage of individual securing screws 23, said shanks being concaved, as at 24 to fit the curved surface 25 of a sector-shaped projection 26 of the carrier I5 and together aggregating a width to completely fill the interval between the end flanges 21 of said projection, see Figs. I and VI.

Set in a longitudinal recess 23 in the surface of the sector projection 26 and secured to the latter block 36. From Figs. IV-VIII, it will be noted that the carrier I5 and the sleeve I1 are cut away respectively at I50. and Na, the resulting voids being in registry and providing a clearance opening through which the screws 29 are passed incident to assembling the block 3|! with said carrier. The voids I5a and Ho also are necessary for clearance of the needles 5 during the descent of the latter. The block 30 has a lengthwise bore 3I (Figs. IX and X) for guid- 32 which passes through an arcuate slot 33 in an integrally formed radial wing 35 of the sleeve I1, said slot being concentric with the shaft I. At its rear end, the latch pin 32 has a tapered head 35 which normally occupies a notch-like enlargement 31 at one end of the slot 33 in the wing 35, as shown in Figs. II, V and VI. The front end of the latch pin 32 is threaded as at 33 for engagement by a thumb nut 39 which has a hollow prolongation 40 fitting a concentric recess H at the corresponding end of the bore 3| in the block 39. A helical compression spring 42 housed partly within the hollow of the thumb nut 39 and partly within the recess H of the block 39, tends to urge the latch pin 32outward, i. e., leftward in Figs. IX and X. Attached to the block 30 by screws 43 is a guide45 with eyes 46 respectively in line with the thread grooves 41 of the loopers 4, by which the looper threads are directed as shown in dot and dash lines in Figs. I and II after passing through an opening 43 in the bearing 3 enroute from a source of supply, not shown.

With the head 36 of the latch pin 32 engaged in the enlargement 31 of the slot 33 in the wing 35 as shown in Figs. II, V, IX, the carrier I5 is locked to the sleeve I-1 and the loopers 4 thereby maintained fixed in their normal positions circumferentially of the shaft I. Accordingly, by oscillation of the shaft I, the loopers 4 are swung back and forth between the limits of retraction and advance respectively, shown in Figs. II and V incident to stitch-formation.

When threading of the loopers 4 is necessary, the cap 6 is first removed from the end of the work-supporting arm 2, and the machine operated by hand to bring said loopers to the normal retracted position shown in Fig. II. The thumb nut 39 is thereupon grasped between the fingers of one hand and thrust inward against the force of the spring 42 to dislodge the head 36 of the latch pin 32 from the notch 31 in the end of the arcuate slot 33 in the wing 35 of the sleeve I1 and thereby free the looper carrier I5. With this accomplished, the thumb nut 39 is shifted clockwise in Fig. II to advance the latch pin 32 along the slot 33 in the wing 35 with attendant movement of the loopers 4 about the shaft I from the position of Fig. II to that of Fig. III where their eyes are conveniently accessible for threading. After threading of the loopers 4, the above procedure is reversed, that is to say: the thumb nut swung anti-clockwise from the III to that of Fig. II in- 36 of thelatch pin 39 is grasped and position of Fig. cident to which the head 32 will be automatically drawn back into the notch 31 of the arcuate slot 33 in the wing 35 under the action of the spring to relock the carrier I5 to the sleeve I1, with consequent restoration of the loopers 4 to the normal circumferential relation with respect to the shaft I. Upon replacement of the end closure cap 6, the machine is once again ready for operation.

Having thus described my invention, I claim:

1. Looper mechanism for sewing machines comprising a shaft; a holder member fixed on the shaft; a looper carrier rotatively free on the shaft but confined against axial-movement relative to the holder member; and latch means whereby the looper carrier is normally locked to the holder member for movement with said shaft, said latch means being releasable to permit limited shifting of the carrier circumferentially of the shaft in relation to the holder member.

'2. Looper mechanism for sewing machines comprising a shaft; a holder member in the form of a sleeve fixed on the shaft with capacity for rotative and endwise adjustment on the shaft; a-

looper carrier on the sleeve confined against axial movement relative to the holder member; and latch means whereby the looper carrier is normally locked to the holder member for movement with the shaft, said latch means being releasable to permit limited shifting of the carrier circumferentially of the shaft in relation to the sleeve.

3. Looper mechanism for sewing machines comprising a shaft; a holder member fixed on said shaft and having a concentric arcuate slot with an enlargement at one end thereof; a looper carrier rotatively free on the shaft but confined against axial movement relative to the holder member; a latchpin on the carrier passing through the arcuate slot of the holder member and having a head normally in engagement with the enlargement of the slot, said pin being axially shiftable for dislodgment of its head from the slot enlargement to permit limited circumferential shifting of the looper carrier about the shaft in relation to the holder member.

4. Looper mechanism for sewing machines comprising a shaft; a holder member in the form of a sleeve adjustably fixed on said shaft, said sleeve having a radial wing with an arcuate slot therein concentric to the shaft and terminating at one end in an enlargement; a looper carrier rotatively free on the sleeve but confined against axial movement relative to the holder member; and a latch pin on the carrier passing through the arcuate slot in the wing aforesaid and having a head normally in engagement with the enlargement of the slot, said latch pin being axially shiftable for dislodgment of its head from the slot looper carrier circumferentially of the shaft in relation to the sleeve.

5. Looper mechanism for sewing machines comprising a shaft; a looper carrier mounted on the shaft and having a curved surface concentric with said shaft between end flanges; a plurality of loopers having anchorage shanks which together aggregate the space between the end flanges of the carrier and which are concaved to fit the curved surface of said carrier; and means whereby the loopers are individually secured to the carrier.

thread guide movable with '6. Looper mechanism for sewing machines comprising a shaft; a holder member fixed on the shaft; a iooper can'ler rotatively free on the shaft but confined against axial-movement relative to the holder member; latch means whereby the looper carrier is normally locked to the holder member for movement with said shaft, said latch means being releasable to permit limited shifting of the carrier circumferentialiy of the shaft in relation to the holder member; and a looper the carrier.

'7. Looper mechanism for sewing machines comprising a shaft; a holder member fixed on the shaft; a looper carrier rotatively free on the shaft but confined against axial movement relative to the holder member; and latch means whereby the looper carrier is normally locked to the holder member for movement with said shaft, said latch means constituting a manipulating element, which, when moved in one direction, effects release of the carrier from the holder, and which, when moved in another direction, causes ,said carrier to be shifted circumferentially of the shaft in relation to the holder.

' 8. Looper mechanism for sewing machines comprising a shaft; a holder member in the form of a sleeve adjustably fixed on said shaft, said sleeve having a radial wing with an arcuate slot therein concentric to the shaft and terminating at' one end in an enlargement; a looper carrier rotatively free on the sleeve but confined against axial movement relative to the holder member; and a latch pin on the carrier passing through the arcuate slot in the wingaioresaid and having a head normally in engement with the enlargement of the slot, said latch pin constituting a manipulating element which, when moved axially, causes dislodgment of its head from the slot enlargement with attendant release of the carrier,- and which, when moved laterally, causes said carrier to be shifted ciroumferentially of the shaft in relation to the sleeve within'the limits of the slot 20 aforesaid.

FRANK A. KUCERA. 

